# Volume XIII. April 2023

In the year that has passed between the previous issue and this one, progress has been made on health, the pandemic seems to be under control, but we are still immersed in the incomprehensible war in Ukraine. We seem unable to stop the unjustified aggression, the show of force and the senselessness.

Our journal has received some very interesting papers from professionals from all over the world, which we would like to share with everyone interested in mathematics. We are sure you will be interested in them.

Investigación

In this paper we perform a statistical study to understand the possible relationship bet- ween several factors and the risk to develop a cardiovascular disease according to the REGICOR test. Once we determine which ones are the risk factors involved, we use a linear regression to measure the relevance of each one of them and get an estimation of the cardio- vascular risk of each patient. With the same factors, we perform a logistic regression to obtain a classification rule for low-moderate risk and high-very high risk.

 Título: Statistical study about the risk factors responsible of coronary events. Autor: Alejandro Fernández-Jiménez, Álvaro Fernández Jiménez & Abilio José Fernández Vicente
Teaching Experiences

The objective of this paper is to propose a methodology for teaching mathematical modeling, via differential equations, in engineering careers. The same part of a diagnosis of the insufficiencies that students of these careers have in the development of basic and elementary skills that limit the development of mathematical modeling ability. The proposed methodology is structured in three stages; level of precision of basic and elementary skills, level of transfer of these skills and level of concretion of mathematical modeling, via differential equations. In the last stage, students in field practices, guided by the teacher, collect information on certain problems of the profession, linked to mathematical modeling and through workshops in the classroom they build mathematical models, via differential equations.

 Título: Methodology for the teaching of the mathematical modeling of problems of the profession, road differential equations Autor: Salvador Fonseca Nueva

Precalculus courses and books do not usually deal with topics directly related to the ones that are to be dealt with later in a Calculus course (limits, derivatives, integrals, series, among others). This work aims at breaking such tradition by introducing a concept that has been called Discrete Derivative and by studying its most important properties and consequences, such as the monotonicity of a real sequence.

 Título: The Discrete Derivative as a propaedeutic concept to a course of Infinitesimal Calculus Autor: Duberly González Molinari

This paper presents the students’ perceptions about the implementation of a teaching proposal, based on the application of mathematics, in particular linear algebra applied to fractal antennas. The didactic interest in Fractal Geometry is recent, constituting a relevant problem, due to its enormous application possibilities. This geometry, very different from the Euclidean geometry, has not yet been widely addressed in Mathematics Education, although it is proposed in the curricula. We applied a 20-item survey to 26 students of a first year of engineering career, to gather their opinions. It was found that engineering students increased their motivation and took advantage of the potential of the proposal, by experiencing mathematics in engineering situations such as fractal antennas.

 Título: Application of Fractal Geometry in the construction of antennas: an assessment of activities in context by engineering students Autor: Victoria Artigue, Joel Gak, María de los Ángeles Fanaro, Gabriela Mombrú & José Job Flores-Godoy

If the law of the excluded third party is assumed, then the counterexamples have a well-defined status in mathematics. In contrast, they have only a modest role in the teaching of mathematics, not very representative of that in professional mathematical activity. In this work, we propose a classification of the Counterexample Situations, which is the product of previous works and an extensive review of school and non-school books, numerous observations of classes and interviews with teachers, future teachers and students. We illustrate each category of this classification with examples taken from school mathematics, thereby seeking to encourage the use of counterexamples, by teachers and university students.

 Título: Counterexample situations in a school context. A classification proposal Autor: Edgardo Locia Espinoza, Armando Morales Carball, Efrén Marmolejo Vega & Héctor Merino Cruz
History of Mathematics

Following the publication of his pioneering treatise on the Calculus of Probabilities, in 1657, Huygens sporadically returns to this issue at the urging of friends and family, through correspondence with them. In 1665 one of these circumstances occurs, at the urging of his friend Hudde. Between the two there is a correspondence on solving specific problems in games of chance among which several variants appear, which the authors introduce throughout the correspondence, on the problem that they themselves called the heads and tails. They agree on the conditions of the problem as the correspondence progresses and, then, they agree on solutions and resolutions, using a 17th century algebraic language. In this work we present translations into Spanish of the fragments of the correspondence that deal with this problem, and we carry out the resolution of the different variants with current algebraic language, but imitating the way of solving them. We propose these problems as an aid in the teaching of this subject for students who are starting in this type of calculation.

 Título: A seventeenth-century probability problem. Huygens and Hudde Autor: José Antonio Camúñez Ruiz & María Dolores Pérez Hidalgo

This communication presents the biographies of fifteen Spanish women pioneers of Mathematics in our country. The main objective is to put them as models and references to society, for which they are practically unknown, even still referring only to the world of Mathematics in Spain. And yet, all of them opened the door for many other women to follow, thus decisively influencing the high current presence of women in Spanish Mathematics.

 Título: Pioneer women of Spanish Mathematics Autor: Juan Núñez Valdés, Adolfo Vázquez Ruiz & Rafael Vázquez Ruiz
Games and Mathematical Oddities

In this article, it is presented a problem about tangencies proposed by our friend and co- lleage Juan José Isach Mayo that serves as an excuse to review different theories about cons- tructions such as inversion or Möbius transformations in the complex plane.

 Título: Around tangents Autor: Francisco Javier García Capitán, Miguel Ángel Pérez García-Ortega, Antonio Roberto Martínez Fernández & Juan Luis Castaño Fernández
Mathematical Tales

This tale is an exercise of narrative synecdoche framed in the course of creative writing (medium level) of the school of literature “Fuentetaja”. The mathematical content of the tale is twofold: on one hand, the topic of the differential equations and its applications is analyzed, on the other hand, the characters of the tale are young mathematicians.

 Título: Segundo jazz Autor: Javier Rodrigo
Critics and Reviews

A group of university professors has written two books on discrete mathematics and graph theory aimed at those readers interested in deepening the study of this subject, which is part of the Computer Engineering curricula, as well as the initial courses in Mathematics studies. As audiovisual support for these books, the authors have created the YouTube chan- nel “El lado discreto de las mates”.

 Título: Youtube channel and books on discrete mathematics and graphs Autor: Cristina Jordán , Marina Murillo-Arcila & Juan B. Seoane Sepúlveda

This article reviews the book Programming in Rust. This book will allow programmers to get introduced to the Rust programming language. It is the language that is being used by the developers of the main operating systems (Windows, Linux, Android) to replace C and C++, due to the improvements it introduces in relation to code security generated, without losing the speed that characterizes C.

 Título: Programación en Rust Autor: Santiago Higuera de Frutos
Interview

We interviewed Miguel Ángel Morales Medina, a mathematician who may be somewhat anonymous to the general public because of his name, but if we say that he is the alma mater of “Gaussianos”, he will surely be quickly identified by most of our readers.

 Título: Miguel Ángel Morales Medina, creator of «Gaussians» Autor: José Manuel Sánchez Muñoz